There are two main types of data storage elements. The first type is volatile memory, in which information stored in a particular storage element is lost the moment the power is removed from the memory. The second type is non-volatile storage element, in which the information is preserved even after the power is removed. Of the second type, some designs allow multiple programming, while other designs allow only one-time programming. Typically, the manufacturing techniques used to form the non-volatile memory are different from standard logic processes. Accordingly, the complexity and the cost for forming the non-volatile memory are high.
Typically, One-Time-Programmable (OTP) memory devices include metal fuses, gate oxide fuses, etc. The metal fuses use metals as programming elements. The gate oxide fuses use gate oxides as programming elements. Existing OTP memory devices were typically fabricated using aluminum interconnect technologies, which involve the steps of aluminum deposition, patterning, and etching. The formation of these OTP memory devices is not compatible with current copper damascene processes, which have become standard processes. In addition, the existing OTP memory devices require either high voltages (such as gate oxide fuses) or high currents (such as metal and via anti-fuses) for programming. Such high voltages or high currents need to be taken into design considerations, and thus the complexity and the cost of fabricating integrated circuits increases accordingly.